Triplon band splitting and topologically protected edge states in the dimerized antiferromagnet

Kazuhiro Nawa, Kimihiko Tanaka, Nobuyuki Kurita, Taku J. Sato, Haruki Sugiyama, Hidehiro Uekusa, Seiko Ohira-Kawamura, Kenji Nakajima, Hidekazu Tanaka

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


Search for topological materials has been actively promoted in the field of condensed matter physics for their potential application in energy-efficient information transmission and processing. Recent studies have revealed that topologically invariant states, such as edge states in topological insulators, can emerge not only in a fermionic electron system but also in a bosonic system, enabling nondissipative propagation of quasiparticles. Here we report the topologically nontrivial triplon bands measured by inelastic neutron scattering on the spin-1/2 two-dimensional dimerized antiferromagnet Ba2CuSi2O6Cl2. The excitation spectrum exhibits two triplon bands that are clearly separated by a band gap due to a small alternation in interdimer exchange interaction, consistent with a refined crystal structure. By analytically modeling the triplon dispersion, we show that Ba2CuSi2O6Cl2 is the first bosonic realization of the coupled Su-Schrieffer-Heeger model, where the presence of topologically protected edge states is prompted by a bipartite nature of the lattice.

Original languageEnglish
Article number2096
JournalNature communications
Issue number1
Publication statusPublished - 2019 Dec 1

ASJC Scopus subject areas

  • General Chemistry
  • General Biochemistry,Genetics and Molecular Biology
  • General Physics and Astronomy


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